Pneumatic leading edge flap for an aircraft wing

ABSTRACT

This invention comprises an expandable pneumatic leading edge flap for an aircraft wing that increases the CL (coefficient of lift) thereof. A thin flexible titanium membrane extends from the stagnation point of the leading edge flap rearwardly along the back surface of the flap to a roller assembly housed within the wing leading edge portion, and an inflatable bag housed within a suitable recess in the lower leading edge portion of the airfoil and enclosed by the leading edge flap when retracted. During high speed flight the bag is deflated and the membrane is stretched taunt so as to define a clean aerodynamic leading edge. When increased lift is desired, the bag is inflated causing the membrane to be unrolled to form an expanded leading edge flap for the wing.

United States Patent 1 James 1 Jan. 16, 1973 [54] PNEUMATIC LEADING EDGEFLAP FOREIGN PATENTS OR APPLICATIONS FOR AN AIRCRAFT WING 7 1,003,0963/1952 France ..244 42 R [75] Inventor: Varnell L. James, Enumclaw,

wash- 98022 Primary Examiner-Milton Buchler [73] Assignee: The BoeingCompany,Seattle,Wash. Assistant Examinercar| Rutledge AttorneyGlennOrlob, Kenneth W. Thomas and [22] Filed: Oct. 26, 1970 Theron Nichols[21] Appl. No.: 84,000 [57] ABSTRACT [52] U.S. Cl. ..244/44 Thisinvention I comprises an expandable pneumatic [51] Int. Cl ..B64c 3/46leading edge flap for an aircraft wing that increases [58] Field ofSearch..244/44, 43, 42 R, 42 D, 42 CA, the C (coefficient of lift)thereof. A thin flexible 244/46 titanium membrane extends from thestagnation point of the leading edge flap rearwardly along the back sur-References Cited face of the flap to a roller assembly housed within theUNITED STATES PATENTS wing leading edge portion, and an inflatable baghoused within a suitable recess m the lower leading 2,378,528 6/1945Arsandaux ..244/44 dge portion of the airfoil and enclosed by theleading 2912,19) 11/1959 edge flap when retracted. During high speedflight the 2382 1/1971- bag is deflated and the membrane is stretchedtaunt so 5O 6/1938 2 384 933 9,1945 as to define a clean aerodynamicleading edge. When 2:504:684 4/1950 increased lift is desired, the bagis inflated causing the 2,763,448 9/1956 membrane to be unrolled to forman expanded leading 2,851,229 9/1958 edge flap for the wing.

6 Claims, 4 Drawing Figures PATENTEDJAN 16 I975 SHEET 1 OF 2 iNVENTOR.

V/IFNELL P nm 16 I975 I 3.711.039

SHEET 2 BF 2 IN VENTOR; mR/vfu L JAMES PNEUMATIC LEADING EDGE FLAP FORAN AIRCRAFT WING SUMMARY OF INVENTION I flexible titanium sheet (or anyother suitable material) connected thereto and this sheet extendsrearwardly back to a roller inside the wing leading edge portion.Between the sheet and rigid leading edge portion is a pneumatic bag. Indeflated condition the flexible titanium sheet is rolled on the rollerin the wing for being pulled taunt and for pulling the rigid flapportion up against the wing and forming the lower wing surface portionof the wing leading edge portion and enclosing the deflated bag in thewing leading edge portion which likewise is stored in a suitable recessin the wing leading edge portion. For takeoffs the pneumatic bag isinflated and the titanium sheet is unrolled, thus causing the leadingedge flap to extend to the takeoff position. For landings a second bagis inflated to swing the leading edge flap slightly further forward to afurther and maximum forward position with unrolling of the reelproviding a maximum C for the wing as a whole for landings. The rigidflap portion has an arcuate pose element pivotally connected to theouter end thereof for forming an aerodynamic curve on the leading edgeof the flap at the stagnation point.

Accordingly, a principal object of this invention is to provide anefficient leading edge flap with pneumatic extension for an aircraftwing.

Another object of this invention is to provide a wing flap which has aflexible membrane enclosing a pneumatic bag on the undersurface of theleading edge flap.

Another object of this invention is to provide a leading edge flap withtwo separately expandable pneumatic bags attached thereto for extendingthe flap from a high speed retracted position to a high lift extendedposition for takeoffs by the inflation of one bag and a further extendedposition for landings by the inflation of both bags.

A still further object of this invention is to provide two expandablepneumatic bags on a leading edge flap wherein tension fibers arepositioned internally of the bags to maintain the proper aerodynamicshape thereof when forming a leading edge flap on a leading edge portionof a wing wherein either one or two bags may be inflated for flapextension.

It has been found that the aforementioned objects can be accomplished toa considerable extent by the disclosed expandable pneumatic leading edgeflap.

Other objects and various advantages of the disclosed pneumatic leadingedge of an aircraft wing will be apparent from the following detaileddescription together with the accompanying drawings, submitted forpurposes of illustration only and not intended to define the scope ofthe invention, reference being made for that purpose to the subjoinedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS The drawings diagrammaticallyillustrate by way of example not by way of limitation, two forms of theinvention wherein like reference numerals designate corresponding partsin the several views in which:

FIG. 1 is a schematic sectional view of a leading edge portion of thewing with the inventive leading edge-flap shown in retracted position insolid lines and illustrated in extended landing position in brokenlines;

FIG. 2 is a view similar to FIG. 1 with the leadin 1 edge flapillustrated in extended high lift positionfo'r takeoffs;

FIG. 3 is similar to a sectional view taken at 33 on FIG. 2 but ofamodified bag; and

FIG. 4 is a side view of a single pneumatic bag utilized in theinvention, with parts in section for clarity of disclosure.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 illustrates schematicallya cross sectional view of a leading edge portion 10 ofa wing 11 having aleading edge flap 12. The leading edge flap 12 comprises a rigid leadingedge portion 13 and an inflatable portion 14. The rigid leading edgeportion 13 is pivotally mounted to the wing leading edge portion 10 witha pivot 15. In FIG. 1, the leading edge flap 12 is illustrated inlanding position in broken lines and is illustrated in retractedposition in solid lines. The inflatable portion 14 comprises pneumaticinflatable bags 16a and 16b which are illustrated with both in deflatedcondition in solid lines in FIG. 1, and a flexible membrane 17 which isillustrated connected to an arcuate pose portion 18 of the rigid leadingedge flap portion 12 and coiled at its other end on a suitable reel 19in a recess 20 in the wing leading edge portion 10. The two bags 16a and16b cause the leading edge flap 12 to assume and maintain either of thetwo positions, slender bag 16b being mounted piggy back style on largerbag 16a. Each bag has its own air supply (not shown), whereby inflationof large bag 16a moves the flap 12 to the takeoff position of FIG. 2 andinflation of the second bag 16b in addition to the first bag 16aactuates the leading edge flap 12 to landing position illustrated by thedotted lines in FIG. 1.

Reel 19 may have a lock for stopping it at each of the two outerpositions, the first position for takeoff and the second, more extendedposition for landing. This reel 19 may be powered with air, electricity,or hydraulic fluid. Membrane 17 may be formed of any suitablenonstretchable and flexible material, such as but not limited totitanium.

For landings, the leading edge flap is extended to a maximum amount forproviding the greatest chord as illustrated in broken lines in FIG. 1.

To deflate the bags and retract the leading edge flap to the finalstored position, a suction may be pulled on the bags.

Link 25 and cowling 26 are secured at the ends of the leading edge flapto overlap the titanium sheet 17. For movement clearance of link 25, aslit may be formed in the end of the sheet 17 adjacent to its connectionto the rigid leading edge portion 13.

FIG. 2 illustrates the leading edge flap l2 actuated to the takeoffposition wherein the rigid leading edge portion 13 is pivoted about itspivot 15 to extended position due to action of only the pneumatic bag16a being inflated. Likewise, upon inflation of the bag the flexiblemembrane 17 has been unrolled from the wing leading edge portion 10 toenclose the lower periphery of the bag 16a. The arcuate pose portion 18of the rigid leading edge portion 12 of the flap is shown extended bythe bag to form the aerodynamic shape of the flap, particularly. at thestagnation point of the flap. As shown in the sectional view of theextended pneumatically inflatable leading edge flap 12 of FIG. 2, dropor tension fibers 21 are illustrated internally of the pneumatic bags16a-and 16b to maintain the proper aerodynamic shape of the bags inconjunction with the flexible membrane 14 around the lower and aftperiphery of bag 16a.

FIG. 3, a section at 3-3 on FIG. 2, illustrates the plurality ofinflatable bags 16a only usually utilized to actuate the rigid leadingedge flap portion 13. Likewise is illustrated the tension fibers 21inside the bags for maintaining the proper aerodynamic shape thereof.

Seals 24 are positioned between sections of the rigid leading edgeportions 13 and each seal 24 is connected to only one portion 13.

FIG. 4 illustrates the bag 16 per. se, with portions shown in sectionfor clarity of disclosure, likewise illustrating the tension fibers 21.

Bag 16 and tension of filament fibers 21 are formed of any flexiblematerial that can be woven into a drop thread type of pressure bag, suchas but not limited to a nylon or stainless steel bag, as "Air Matt"manufactured by Goodyear. The material nylon is utilized if theoperating temperatures do not exceed IF, and stainless steel is used foroperating temperatures over I20F and pressures over 10 p.s.i.

Tabs 22 and 23 on the bag may be connected to flap structure with flatheaded screws.

Accordingly, itwill be seen that the present pneumatic leading edge foran aircraft wing operates in a manner which meets each of the objectsset forth hereinbefore.

While only two embodiments of the invention have been disclosed, it willbe evident that various modifications are possible in the arrangementand construction of the disclosed pneumatic leading edge for an aircraftwing without departing from the scope of the invention. And, it isaccordingly desired to comprehend within the purview of this invention,such modifications as may be considered to fall within the scope of theappended claims.

Iclaim:

1. A variable lift aircraft wing comprising: a leading edge portion forthe aircraft wing; flap means comprising a structurally rigid panelportion movably carried by said wing leading edge portion; actuatingmeans comprising a pneumatically deformable unitary bag having internalmembers for maintaining the shape of the inflated form to apredetermined contour; said actuating means interconnecting the flapwith the undersurface of the leading edge portion of the wing forextending the flap to an operative forward and downward extendedposition for changing said aircraft wing to a high lift wing forlandings and takeoffs; and said actuatmg means being col la sible to agreatly reduced v0 ume for retractlonin 0 said wing leading edge portionfor converting said aircraft wing into a low drag, high speed wing. 1

2. A variable lift aircraft wing as recited in claim 1, wherein: saidflap structurally rigid panel portion has first and second ends; saidfirst end of the panel portion being pivotally connected to said wingleading edge portion; and arcuate nose portion being pivotally connectedto said second end of said flap panel portion; and said arcuate noseportion also being connected to said inflatable actuating means wherebysaid arcuate nose portion is pivoted forwardly relative to said flappanel portion by said inflatable actuating means for increasing thechord and camber of said wing, and said arcuate nose portion is .pivotedin the oppositev direction rearwardly relative to said structurallyrigid panel portion by said inflatable actuating means for decreasingthe chord and camber of said wing.

3. A variable lift aircraft wing as recited in claim .1, wherein: saidactuating means when fully inflated forms an external shape thatconforms to the undersurface of the flap panel portion in its extendedpositionand encloses the area between the leading edge portion of theflap panel and the undersurface of the leading edge portion of the wingso as to form an enclosed convex aerodynamic leading edge flap for thewing.

4. A variable lift aircraft wing as recited in claim 3, wherein: saidactuating means comprises two inflatable bags secured between said wingleading edge portion and said flap panel portion; the second of saidbags being positioned on top of the first bag and in abutment relationwith the undersurface of the flap panel portion such that when both bagsare inflated, the movably mounted flap panel portion is extendable to agreater amount for increasing the chord and camber of the aircraft wingthan when only one of said bags is inflated.

5. A variable lift aircraft wing as recited in claim I, furtherincluding: a flexible sheet interconnecting the leading edge of the flapwith the undersurface of the leading edge portion of the wing forenclosing the undersurface of the pneumatically deformable bag when inthe inflated form.

6. A variable lift aircraft wing as recited in claim 5, wherein: one endof said flexible sheet is fixedly connected to the leading edge of theflap and the other end of the sheet is rolled on a reel attached to theundersurface of the leading edge portion of the wing whereby the sheetis reeled out as the actuating means is inflated and reeled in when theactuating means is deflated.

1. A variable lift aircraft wing comprising: a leading edge portion forthe aircraft wing; flap means comprising a structurally rigid panelportion movably carried by said wing leading edge portion; actuatingmeans comprising a pneumatically deformable unitary bag having internalmembers for maintaining the shape of the inflated form to apredetermined contour; said actuating means interconnecting the flapwith the undersurface of the leading edge portion of the wing forextending the flap to an operative forward and downward extendedposition for changing said aircraft wing to a high lift wing forlandings and takeoffs; and said actuating means being collapsible to agreatly reduced volume for retraction into said wing leading edgeportion for converting said aircraft wing into a low drag, high speedwing.
 2. A variable lift aircraft wing as recited in claim 1, wherein:said flap structurally rigid panel portion has first and second ends;said first end of the panel portion being pivotally connected to saidwing leading edge portion; and arcuate nose portion being pivotallyconnected to said second end of said flap panel portion; and saidarcuate nose portion also being connected to said inflatable actuatingmeans whereby said arcuate nose portion is pivoted forwardly relative tosaid flap panel portion by said inflatable actuating means forincreasing the chord and camber of said wing, and said arcuate nosePortion is pivoted in the opposite direction rearwardly relative to saidstructurally rigid panel portion by said inflatable actuating means fordecreasing the chord and camber of said wing.
 3. A variable liftaircraft wing as recited in claim 1, wherein: said actuating means whenfully inflated forms an external shape that conforms to the undersurfaceof the flap panel portion in its extended position and encloses the areabetween the leading edge portion of the flap panel and the undersurfaceof the leading edge portion of the wing so as to form an enclosed convexaerodynamic leading edge flap for the wing.
 4. A variable lift aircraftwing as recited in claim 3, wherein: said actuating means comprises twoinflatable bags secured between said wing leading edge portion and saidflap panel portion; the second of said bags being positioned on top ofthe first bag and in abutment relation with the undersurface of the flappanel portion such that when both bags are inflated, the movably mountedflap panel portion is extendable to a greater amount for increasing thechord and camber of the aircraft wing than when only one of said bags isinflated.
 5. A variable lift aircraft wing as recited in claim 1,further including: a flexible sheet interconnecting the leading edge ofthe flap with the undersurface of the leading edge portion of the wingfor enclosing the undersurface of the pneumatically deformable bag whenin the inflated form.
 6. A variable lift aircraft wing as recited inclaim 5, wherein: one end of said flexible sheet is fixedly connected tothe leading edge of the flap and the other end of the sheet is rolled ona reel attached to the undersurface of the leading edge portion of thewing whereby the sheet is reeled out as the actuating means is inflatedand reeled in when the actuating means is deflated.